Current state-of-the-art fire protection engineering technology relies heavily upon sprinkler systems to contain and control fire in a building. Sprinklers are active systems which require water pressure, pumps, and piping. If any of these three components are damaged, the entire system is usually rendered useless. Such damage to sprinkler system components can occur in many ways. For example, if an earthquake severs a water main and effects water pressure, the sprinkler system may not operate. Or, if a fire occurs during an electrical blackout, or if the fire damages the building's electrical system, the pumps may be rendered inoperative. Relatively less attention has been paid to compartmentalization and fire resistive construction. These so-called "passive systems," while not providing the advantages of a sprinkler system with regard to extinguishing a fire, nonetheless afford significant advantages in terms of containing a fire. Once these passive systems are properly installed, there is no dependency upon outside factors to perform their tasks. Additionally, the cost of such systems is usually substantially less than a sprinkler system.
In the field of fire resistive construction, very little attention has been paid to the structural voids or separations, commonly called "joints," in buildings and parking structures. Such joints typically occur between adjacent wall structures or adjacent floor structures and are often found in roof construction. Joints may be either static or dynamic, a dynamic joint being a joint which opens and closes to accommodate movement of the adjacent structures such as wind loading or thermal expansion and contraction. An apparatus installed within a static joint to inhibit the spread of fire through the joint is commonly referred to as a "fire stop," while an apparatus installed within a dynamic joint to inhibit the spread of fire is commonly referred to as a "fire barrier." However, for the sake of convenience, the term "fire barrier" as used herein will be understood to encompass both fire stops and fire barriers. If a joint is not fire protected, a devastating catastrophic results called the "chimney effect" can cause fire, toxic gases, and smoke to spread rapidly throughout the structure. Thus, there is a need to provide a fire barrier system to prevent the rapid spread of fire, smoke, and toxic gases through unprotected joints.
Prior efforts have been made to provide fire barrier systems to prevent the spread of fire through joints. However, these prior art systems typically suffer a number of disadvantages. First, the majority of such systems are "directional" in nature, meaning that they resist the spread of fire from one side of the barrier better than from the other side. While such systems might be acceptable if it could always be known on which side of the joint a fire will occur, such is seldom the case. Thus, in order to afford the desired degree of protection, the fire barrier must be selected so that its less resistant side meets the necessary requirements. Consequently, the other side of the fire barrier may provide substantially more protection than is actually needed. While there is no disadvantage per se to extending the desired degree of protection, such excess generally translates into increased expense of the fire barrier. Alternatively, mutually opposing fire barrier systems may be installed within the same joint, each of which meets the minimum standard. Again, however, the installation of two separate barriers results in increased cost of installation.
Another problem arises in testing prior art fire barriers to determine their fire resistance rating. A nationally accepted and utilized fire test standard called ASTM E119, Standard Test Methods for Fire Test of Building Construction and Materials, rates a wall construction in terms in the length of time which the wall construction maintains all the criteria of the fire test standard. With prior art fire barrier systems, it has been necessary to conduct two separate tests of a given wall construction, one test from either side of the asymmetrical fire barrier, to assign separate ratings to each side of the fire barrier. Since the expense associated with conducting a single test is considerable, it would be desirable to provide a fire barrier system whereby both sides of the barrier can be rated without requiring multiple tests.